1. Field of the Invention
This invention relates to a single very light tubular building element for the construction of reinforced concrete intermediate floors/ceilings and roofs. The single building element provides the formwork for the casting in place of the structural concrete and also provides for a high quality finished ceiling at the same time. It is intended for simple installation without heavy equipment into building parts. A series of members are often intended to form an exposed surface when used as a floor or ceiling.
A series of members are constructed and often disposed to be the primary means of containing and supporting a panel or slab of concrete as it cures. An interconnected series of members, according to the present invention, also form a continuous mortar impervious formwork for a concrete slab, and presents an attractive permanently exposed ceiling surface.
2. Prior Art
There have been many suggestions for use of either or both temporary or permanent form members to construct building parts of concrete. These form members can be temporary in nature because they are removed after concrete cures, or can be contained in concrete as permanent parts. For example:
U.S. Pat. No. 5,953,880 to de Zen teaches a modular building system of extruded hollow thermoplastic structural components of rectilinear cross-section. These members are made of a special thermoplastic mixture said to resist the elements and are characterized by a fire-resistant outer skin. The concrete is poured inside the thermoplastic components that have internal apertures through which the concrete can flow from one member to another member in a group when they are joined as a wall panel, for example. When the members are to be used in construction of a roof, concrete cannot be used, and metal inserts are called for to assist in stiffening.
U.S. Pat. No. 5,729,944 to de Zen discloses the use of thermoplastic structural components as permanent formwork. The forms can be used in a series to construct various structures. Concrete is poured inside the thermoplastic components that have internal apertures through which the concrete can flow from one member to another member when they are joined as a wall panel.
U.S. Pat. No. 5,397,096 to Nelson is illustrative of conventional concrete forming techniques to manufacture a ribbed, reinforced concrete slab. The forming system utilizes concrete displacement pans supported on temporary framework. Nelson discloses the problem of concrete leaking out of joints. The leaking material normally is without aggregate, and is sometimes referred to as mortar. When the concrete slab or slab cures, workers must, remove the hardened mortar with a chisel, or the like, providing an unsatisfactory surface finish. The bottom surface is neither planar nor finished. Nelson suggests the use of additional members to forestall the leakage of mortar.
U.S. Pat. No. 4,557,031 to Winkler and U.S. Pat. No. 5,216,863 to Nessa et al. are illustrative of other expedients to join extruded plastic form members for use in containing concrete inside. The members are normally a part of the cured concrete structure or building component.
U.S. Pat. No. 5,535,565 to Majnaric et al. is illustrative of a containment including a plurality of panels that are interconnected by connector columns and fused together by the passing of electrical current through conductors received within such elements at their points of intersection. Sliding one adjacent panel over another panel interconnects the panels. A gasket is interposed between a pair of panels to create a watertight environment.
U.S. Pat. No. 4,742,660 to Vadala is illustrative of a highly sound insulating clay tile for the construction of floors that has an outer substantially parallelepiped shape with symmetrical, laterally projecting portions that act as shoulders for the support of each tile by prefabricated reinforced concrete floor beams.
While the field of reinforced concrete formwork is well developed, there is still the need for a relatively inexpensive easy-to-use system to form ribbed-concrete slabs with structural formwork components. The system should not be as labor intensive as prior art configurations. It should use components that are lightweight and yet will control elastic deformation such as is often encountered when steel and aluminum alloy formwork is used to make such ribbed structures. Moreover, each element should be easily aligned with an adjacent member, the alignment measures providing an impermeable alignment between adjacent members. Thus, eliminating the need of additional members (e.g., gaskets) or fusing of the adjacent members to accomplish impermeability.
Further, the members making up the formwork should not be filled with concrete to create the slab. Similarly, the members should include an easy device for placement of reinforcement bars without the need of manual tying or securing of the reinforcement bars together.
It is also desirable to have the ability to incorporate the formwork into the slab and have it serve as an impervious formwork base, eliminating cumbersome cleaning during construction and leakage afterward, and saving the common need of a costly waterproofing membrane over the slab. The formwork should serve for the casting in place of the structural concrete and also should provide for a high quality finished ceiling at the same time, eliminating the need to plaster and otherwise enhance the aesthetic appeal of the ceiling. Finally, the formwork should facilitate hung ceiling installations and also be easily penetrable to hold threaded screws and the like.